The human eye can suffer a number of maladies causing mild deterioration to complete loss of vision. While contact lenses and eyeglasses can compensate for some ailments, ophthalmic surgery is required for others. Generally, ophthalmic surgery is classified into posterior segment procedures, such as vitreoretinal surgery, and anterior segment procedures, such as cataract surgery. More recently, combined anterior and posterior segment procedures have been developed.
The surgical instrumentation used for ophthalmic surgery can be specialized for anterior segment procedures or posterior segment procedures or support both. In any case, the surgical instrumentation often requires the use of associated consumables such as surgical cassettes, fluid bags, tubing, handpiece tips and other consumables.
A surgical cassette can provide a variety of functions depending on the procedure and surgical instrumentation. For example, surgical cassettes for cataract surgeries (e.g., phacoemulsification procedures) help manage irrigation and aspiration flows into and out of a surgical site. Surgical cassettes can also provide support for fluid bags, a manifold for directing vacuum/pressure to surgical instrumentation, and other functionality.
During a surgical procedure, such as a cataract surgery, fluid flow is controlled by valves within the surgical cassette. However, current cassette designs utilize valves that are classified as “normally open,” meaning that the valves are open unless they are actively engaged in order to close them. These normally open valves allow fluid ingress into the cassette's (and therefore the surgical system's) aspiration path during cassette installation and removal. Further, normally open valves can result in the dribbling of liquids from the cassette ports when removed from the receiver, which limits the overall cleanliness of a surgical procedure. Further still, for some applications, normally open valves do not “fail safe” in a loss of power situation, resulting in potentially unwanted fluid flow when power is lost.
Therefore, a need exists for a cassette valve design that can control the flow of liquids within the cassette while reducing or eliminating the problems of prior art cassette valve designs and that can provide increased functionality, reliability, cleanliness and safety.